Enzymuria (the output of gamma-glutamyl-transpeptidase and of N-acetyl-beta-D-glucosaminidase) in the course of experimental renovascular hypertension

Production of bioactive plant secondary metabolites through in vitro technologies-status and outlook

Medicinal plants have been used by mankind since ancient times, and many bioactive plant secondary metabolites are applied nowadays both directly as drugs, and as raw materials for semi-synthetic modifications. However, the structural complexity often thwarts cost-efficient chemical synthesis, and the usually low content in the native plant necessitates the processing of large amounts of field-cultivated raw material. The biotechnological manufacturing of such compounds offers a number of advantages like predictable, stable, and year-round sustainable production, scalability, and easier extraction and purification. Plant cell and tissue culture represents one possible alternative to the extraction of phytochemicals from plant material. Although a broad commercialization of such processes has not yet occurred, ongoing research indicates that plant in vitro systems such as cell suspension cultures, organ cultures, and transgenic hairy roots hold a promising potential as sources for bioactive compounds. Progress in the areas of biosynthetic pathway elucidation and genetic manipulation has expanded the possibilities to utilize plant metabolic engineering and heterologous production in microorganisms. This review aims to summarize recent advances in the in vitro production of high-value plant secondary metabolites of medicinal importance.

Key points

• Bioactive plant secondary metabolites are important for current and future use in medicine

• In vitro production is a sustainable alternative to extraction from plants or costly chemical synthesis

• Current research addresses plant cell and tissue culture, metabolic engineering, and heterologous production

Clinical utility of urine kidney injury molecule-1 (KIM-1) and gamma-glutamyl transferase (GGT) in the diagnosis of canine acute kidney injury

The aim of the present study was to evaluate the sensitivity and specificity of urine KIM-1 and urine GGT for the detection of naturally-occurring AKI, compared to healthy control dogs, dogs with stable chronic kidney disease (CKD), and dogs with lower urinary tract disorders (LUTD). The study included AKI grade 1 (n = 21), AKI grade 2 to 5 (n = 11), stable CKD (n = 11), LUTD (n = 15), and healthy dogs (n = 37). Urine KIM-1 (ng/mg) and GGT (U/l) were normalized to urine creatinine (uCr). Statistically significant difference in KIM/uCr (p = 0.0007) and GGT/uCr (p < 0.0001) was found among the study groups. Area under the curve (AUC) for KIM-1/uCr and GGT/uCr as predictors of AKI was 0.81 and 0.91 respectively. Values of KIM-1/uCr of 0.73 ng/mg and of GGT/uCr of 54.33 showed the best combination of sensitivity and specificity (75% and 75.6%; 85.7% and 89.1% respectively). A significant positive correlation (p < 0.0001) between KIM-1/uCr and GGT/uCr was found. Both urine KIM-1/uCr and GGT/uCr seemed to be potentially good markers for the diagnosis of AKI. Dogs with AKI showed significantly higher levels of urine KIM-1/uCr and urine GGT/uCr, compared with healthy dogs. Caution should be used in the evaluation of elevated urine KIM-1/uCr and GGT/uCr in dogs with pre-existing CKD and/or LUTD. Urine KIM-1/uCr and GGT/uCr might have a significant clinical utility, as complementary test, particularly in diagnosis early, non-azotemic stages of AKI.

Utility of urinary alkaline phosphatase and γ-glutamyl transpeptidase in diagnosing acute kidney injury in dogs

The diagnostic utility of urinary alkaline phosphatase (uALP) and γ-glutamyl transpeptidase (uGGT) activities in naturally occurring acute kidney injury (AKI) was investigated in a heterogeneous group of dogs. The study included client-owned dogs with AKI (n = 32), chronic kidney disease (CKD, n = 13), lower urinary tract infection (LUTI, n = 15) and healthy controls (n = 24). uGGT and uALP activities were normalised to urinary creatinine (uCr) concentrations (uGGT/uCr and uALP/uCr, respectively). uALP/uCr and uGGT/uCr were positively and significantly correlated (r = 0.619, P <0.001), and differed significantly (P ≤ 0.001) among groups, as well as between AKI and LUTI or CKD groups (P < 0.05), but not between the AKI and control groups. Areas under the receiver operator characteristics (ROC) curve for uALP/uCr and uGGT/uCr as predictors of AKI were 0.75 and 0.65, respectively, with optimal cut-off points showing poor to moderate sensitivity (59% for uALP/uCr and 79% for uGGT/uCr) and specificity (59% for uALP/uCr and 75% for uGGT/uCr). Higher cut-off points, with 90% specificity, showed low sensitivity (41% for both uALP/uCr and uGGT/uCr). In conclusion, uALP/uCr is superior to uGGT/uCr as a marker of AKI, but both uGGT/uCr and uALP/uCr have unsatisfactory discriminatory power for diagnosing naturally occurring AKI in dogs and therefore cannot be recommended as sole screening tests for canine AKI. However, both may serve as ancillary, confirmatory, biomarkers for detecting AKI in dogs if appropriate cut-off points with high specificities are used.

Morphological correlates of urinary enzyme loss after extracorporeal lithotripsy

Urinary loss of the tubular marker enzyme N-acetyl-beta-D-glucosaminidase (NAG) immediately following extracorporeal lithotripsy suggests corresponding morphological changes in the kidney. To date, the morphological correlate of the enzymuria remains unclear. In this animal study with Wistar rats acute morphological changes in the tubulus cells beneath isolated tubulus necrosis were demonstrated. The mechanically induced lesions of the cell organelles included fragmentation of the lysosomes and severe alterations of the cell membrane. The tubulus damage was quantified. With the help of histochemical NAG staining and electron microscopic observations, a significant correlation between number and intensity of shock waves and tubular damage was found. The intracellular lesions described here are at least part of the morphological basis of shock-wave-induced enzymuria. The results show that enzymatic changes in urine reflect visible renal damage.

Urinary excretion of enzymes in cirrhotics with renal failure

We studied the significance of urinary enzyme measurements in diagnosing proximal tubular damage in cirrhosis of the liver. Urinary excretion (u-enzyme) and fractional urinary excretion (FEenzyme) of gamma-glutamyltranspeptidase (GGT), leucine aminopeptidase (LAP), alkaline phosphatase (AP) and beta-glucuronidase (B-GLU) were quantified in 14 control subjects (group I), 12 cirrhotics with functional renal failure (group II), 13 cirrhotics with renal tubular damage (group III) and 7 non-liver patients with renal tubular damage (group IV). Urinary enzyme excretion and fractional enzyme excretion were significantly higher in the cirrhotics of group III than in the controls or group II. In group III, these tests usually reached values within the range of group IV. The sensitivity of urinary enzyme excretion was 0.92 and specificity ranged from 0.75 (u-LAP) to 1 (u-GGT; u-B-GLU). The sensitivity of fractional enzyme excretion was between 0.61 (FEB-GLU) and 0.84 (FEGGT; FELAP), while specificity was from 0.91 (FELAP; FEAP) to 1 (FEGGT; FEB-GLU). The results indicate that measurement of urinary enzymes may be very useful in diagnosing renal tubular damage in cirrhotic patients with impaired renal function.

Significance of the measurement of urinary alanine aminopeptidase and N-acetyl-beta-D-glucosaminidase activity in evaluating patients with essential hypertension

To examine the relationship between the urinary levels of alanine aminopeptidase (AAP) or N-acetyl-beta-D-glucosaminidase (NAG) and the advance of essential hypertension, we measured the urinary levels of these enzymes in 20 normotensive controls, 8 subjects with borderline hypertension and 40 subjects with WHO stage I and stage II essential hypertension. The urinary level of NAG in stage II hypertensives was higher than that in the normotensives, and borderline or stage I hypertensives (p less than 0.01). Systolic blood pressure and the urinary level of NAG was positively correlated in hypertensives (rs = 0.43, p less than 0.01). The urinary level of NAG was correlated inversely with renal blood flow (rs = -0.61, p less than 0.01). The urinary level of AAP in stage II hypertensives was also higher than that in the normotensives (p less than 0.01) or stage I hypertension (p less than 0.01), but the urinary AAP level was not significantly correlated with systolic blood pressure or renal blood flow in hypertension.